(1) Field of the Invention
The present invention relates to a pressure welding connecting terminal, which is electrically connected to a core wire of an electric wire that includes an electrically insulating coating on an outer circumference of the core wire, the insulating coating being cut when the electric wire is press-fit into a slot of a pressure welding piece, and to a pressure welding connector that receives the pressure welding connecting terminal therein.
(2) Description of the Related Art
FIG. 7 shows an example of a conventional pressure welding connecting terminal and a pressure welding connector that receives the pressure welding connecting terminal therein (Japanese Patent Application Laid-Open No. H6-203888).
In this conventional example, a connector housing 56 is provided with a hollow part 57 and a pressure welding connecting terminal 50 is provided with a step 54b and wire-fixing part 54, which engage with the hollow part 57, so that an electric wire 60 never comes out from the pressure welding connecting terminal 50 even if a tension is applied thereon, thereby the electric wire 60 is securely held without using an external component such as a holding member.
The pressure welding connecting terminal 50 is formed by stamping out from an electrically conductive plate and by being bent. The pressure welding connecting terminal 50 includes a female electric contact 51 having a rectangular cylindrical shape at one side thereof and a wire-pressure welding part 52 and wire-fixing part 54 at the other side. A resilient contact piece (not shown) is provided in the electric contact 51 and a male terminal (not shown) of a mating connector is inserted into the electric contact 51 from a hole (not shown) in a front wall 58b of the connector housing 56 made of synthetic resin.
The wire-pressure welding part 52 (hereinafter, pressure welding part 52) includes a pair of side walls 52a, each rising up vertically from both sides of a horizontal base plate 53, and respective pairs of pressure welding pieces 52b, each pair being bent inwardly at the front and rear ends of the side wall 52a. A slot 53c for pressure-welding the wire is formed between the pair of the pressure welding pieces 52b. An insulating coating of the electric wire 60 is cut by a blade situated at an upper end of each pressure welding piece 52b. A core wire of the electric wire 60 is press-fit into the slot 52c, so that the wire 60 is connected to the pressure welding connecting terminal 50.
The wire-fixing part 54 situated at the rear of the pressure welding part 52 includes a pair of crimp pieces 54a formed alternately, which caulks the circumference of the coating of the wire 60 so as to fix the wire 60. Since the pressure welding part 52 is thin, its strength is small. Therefore, the pressure welding part 52 might be inclined or deformed depending on a tension of the wire 60, however, since the wire-fixing part 54 fixes the wire 60, the pressure welding part 52 is prevented from being inclined.
The pressure welding connecting terminal 50 is inserted into a terminal-receiving groove 59 of the connector housing 56 from above and engaged with an engaging projection 59a. Under such a condition, the wire 60 is pressure-welded to the pressure welding part 52 from above. This pressure welding is carried out in a manner that the wire 60 is press-fit from above with a press-fitting blade (i.e. jig) keeping away from the pressure welding piece 52b. In comparison with the crimping, the pressure welding has an advantage that it saves a time-consuming work because it does not need a work of peeling the insulating coating.
The terminal-receiving groove 59 of the connector housing 56 is surrounded by left and right partition walls 58a (only one of them being shown in the figure), side wall 58c and front wall 58b. The connector housing 56 is received in a casing (not shown in the figure), thereby an upper opening of the terminal-receiving groove 59 is covered. A pressure welding connector 55 is constituted by at least the connector housing 56 and the pressure welding connecting terminal 50.
The pressure welding piece 52b of the pressure welding connecting terminal 50 is formed integrally with the side wall 52a. In contrast, in FIG. 8, there is shown a pressure welding connecting terminal 65 which includes a pressure welding piece 67c having no side wall. In this pressure welding connecting terminal 65, folding part 67a formed on a side of a base plate 66 is folded by an angle of 180° in a U-turn-shape, then a connecting part 67b that leads to the folding part 67a is piled on the base plate 66 and then, the pressure welding piece 67c formed at an end of the connecting part 67b is bent inwardly by an angle of 90°, thereby forming a pressure welding part 67.
As another conventional example (not shown), a pressure welding connecting terminal has been proposed (Japanese Patent Application Laid-Open No. H6-203643 and Japanese Patent Application Laid-Open No. H11-40214), in which a pressure welding part made of metal is formed separately from a base plate, a notched part is formed on a base plate or side wall, and the pressure welding part is engaged with the notched part so as to be fixed.
However, the conventional pressure welding connecting terminal 50, 65 described above has the following problem.
In the first conventional example (FIG. 7), the pressure welding piece 52b leads to the side wall 52a that rises up vertically from both sides of the horizontal base plate 53, therefore the rising-up posture of the pressure welding piece 52b is stabilized so as to prevent the pressure welding piece 52b from being inclined in a direction of its thickness upon press-fitting of the wire. However, on the other hand, the thickness of the wide wall 52a is included into the width dimension of the pressure welding connecting terminal 50, causing an increase in the width of the pressure welding connecting terminal 50. If the width of the pressure welding connecting terminal 50 is large, the width of the terminal-receiving groove 59 of the connector housing 56 that receives the pressure welding connecting terminal 50 therein becomes large, causing difficulty in making the pressure welding connector 55 compact. Particularly, as for a multipolar connector, a demand for making the connector compact has been strong.
In FIG. 8, when the folding part 67a is short, the connecting part 67b that leads to the folding part 67a is piled on the base plate 66 being displaced. However, if the folding part 67a is made long, it causes a problem that the folding part 67a is forced out toward the outside in the width direction of the base plate 66.
In the other conventional example described above, the pressure welding part is formed separately from the base plate. Since there is the side wall that rises up perpendicularly from the side of the base plate similarly to the first conventional example, there has been a problem that the width dimension of the pressure welding connecting terminal becomes large and a problem that the number of the components is increased, causing a cost-up of the components.